This activity teachesConcept C - Greenhouse Effect. The amount of solar energy absorbed or radiated by Earth is modulated by the atmosphere and depends on its composition. Greenhouse gases— such as water vapor, carbon dioxide, and methane— occur naturally in small amounts and absorb and release heat energy more efficiently than abundant atmospheric gases like nitrogen and oxygen. Small increases in carbon dioxide concentration have a large effect on the climate system.

Goals

Students should be able to do the following:

Explain how the greenhouse effect works, in terms of several basic physical principles applied to long-term, global average energy budgets for the atmosphere and the earth's surface.

Explain why adding greenhouse gases to the atmosphere unbalances the energy budgets for the atmosphere and the earth's surface and leads to global warming.

Description

In this activity(Microsoft Word 2007 (.docx) 283kB Jun15 11), students, working in small groups, respond to a series of questions asking them to analyze a diagram of the long-term, global average energy budgets for the atmosphere and the earth's surface (below). They then are asked to explain how the greenhouse effect works in terms of several basic physical principles applied to their analysis. Finally, they are asked to apply the same principles to the predict changes in global average atmospheric and surface temperatures as a result of adding greenhouse gases to the atmosphere.

Assessment

Formative assessment: The instructor circulates among the groups, monitoring their progress, and addresses conceptual difficulties of individual groups or the class as a whole as needed.

Formative assessment: At several points during the activity itself, the instructor asks randomly selected students to communicate their group's response (and reasoning) for individual questions, and facilitates discussion, provides supplemental instruction, and reinforces points, as needed.

Summative assessment: Multiple choice or matching questions about many aspects of the energy budget diagram can be formulated and administered on a quiz or exam. Explanations of how several basic physical principles applied to the long-term, global average energy budgets tell us (1) how the greenhouse effect works, and (2) how adding greenhouse gases would lead to warmer global average temperatures, would better be solicited as a short essay question on a quiz or exam, though other assessments are possible.

Connections to other Activities

This activity is one of a suite of five activities designed to address the concepts that address how the greenhouse effect influences global temperature (Principle 2, Concept C) which can be used individually or combined as desired.

A recommended "warm-up" activity to prepare students better to tackle this one might be What is the Earth's Average Temperature, in which students apply the same basic physical principles to satellite observations of the planetary energy budget to determine the average temperature of the planet as a whole and contrast that with the global average surface temperature.